Theresa May’s massive political miscalculation could destabilize the Good Friday Agreement’s fragile power-sharing scheme at the worst possible time.

The drama in the aftermath of the United Kingdom’s general election last week has occurred mostly in London. There, the typical questions come up: Will Theresa May remain as prime minister, or will one of her comrades — Boris Johnson, perhaps — seek to oust her? Will there be another general election this year? What is the future of Brexit? Could Jeremy Corbyn cobble together an alliance with the Liberal Democrats and Scottish Nationalists and enter Downing Street as prime minister? (That last one’s a long shot.)

Across the Irish Sea, the election’s consequences are perhaps even more significant. Much of the discussion around May’s rumored confidence-and-supply agreement with the Democratic Unionist Party has focused on that party’s austere social conservatism — its opposition, in near-absolute terms, to abortion and gay marriage, for instance. Largely unexplored, though, especially in the United States, is the seemingly imminent breakdown of devolved government in Northern Ireland, a political crisis that has only worsened since the election.

The political system established by the Good Friday Agreement nearly 20 years ago is a fragile, tricky thing. In Westminster, one party rules all; in Northern Ireland, the long history of partisan violence and enmities has necessitated a scheme predicated on power-sharing and cooperation. The intent is to ensure that government remains consociational, never dominated by one religious group over the other. Cabinet positions in the Northern Ireland Executive, for instance, are distributed between the two largest parties, typically one unionist and one republican — before his resignation in January, the late Sinn Fein leader Martin McGuinness served as deputy first minister alongside DUP leader Arlene Foster. The agreement mandates that the withdrawal of one party from the Executive would cause the entire government to collapse, and a failure to reach a new power-sharing deal would mean the reintroduction of direct rule from Westminster, the status quo throughout the Troubles. The British and Irish governments are meant to affirm neutrality, expressing no opinion on the political future of the province, instead letting politics there proceed unfettered.

Since 1998, Northern Ireland has — apart from sporadic periods of direct rule imposed in crisis — largely governed itself within the structure of the Good Friday Agreement, free of excess interference from Britain. Now, though, that system finds itself buffeted by political crisis, making its collapse and a return to political chaos seem all too likely.

The origins of Northern Ireland’s current political predicament can be traced back to a good old-fashioned scandal. In 2012, the devolved government established something called the Renewable Heat Incentive Scheme, run by Foster, then holding a ministerial position. The plan was intended to effect a country-wide shift away from traditional heating toward more sustainable energy by paying households to use the latter. But its fundamental structure was faulty — without a cap on energy use, users could stand to make a net profit from heating their homes or various unattended structures on their properties. (In Britain, similar schemes imposed a cap, thus avoiding the problem.) The resulting cost to the devolved government was exorbitant, some £400 million over the next 20 years.

As the enormous size of the scheme’s problem came to light, the brunt of the blame fell on Foster, given her leadership of the department at the time. The crisis came to a head in January, when McGuinness resigned from his position as deputy first minister in protest of Foster’s refusal to allow an independent inquiry into her conduct to proceed.

The DUP’s quasi-introduction into government only makes the process of bargaining for the region’s post-Brexit future harder.

The resignation of McGuinness — who died two months later — and the subsequent inability of Sinn Fein and the DUP to arrive at a power-sharing deal forced a new election for the Northern Ireland Assembly, the second in two years. Sinn Fein won 28 percent of the vote, its best-ever showing, making it the second-largest party in the assembly. The DUP garnered 28.1 percent of the vote, losing ten seats to come away with a total of 28.

After the elections came a second round of talks to restore power-sharing. Overseen by James Brokenshire, secretary of state for Northern Ireland, the talks took place under the threat that Westminster would reimpose direct rule if they failed. Theresa May’s ill-conceived general election, occurring in the middle of the fracas, revealed a disturbing trend: the social democrats (SDLP) and Ulster Unionists, moderate republican and unionist parties respectively, won no seats and saw their vote shares collapse, while the more radical Sinn Fein and DUP gained ground.

What has thrown the situation into veritable crisis, though, is the disappointing performance of May’s Tories, who now find themselves forced to rely on the votes of the small DUP bloc to prop up their government in Westminster. The introduction of a Northern Irish party into a quasi-coalition in Westminster is an unprecedented occurrence, one with the potential to further upset the province’s increasingly precarious settlement.

The first elemental concern is for a fundamental tenet of the Good Friday Agreement: the neutrality of the United Kingdom. In the words of Jonathan Powell, an adviser to Tony Blair who worked on the agreement, this amounts to a pledge that Britain “has no selfish strategic or economic interests in Northern Ireland.” Without such a pledge, Britain cannot serve as a functional mediator in negotiations between the two sides of the conflict. This view is, it seems, supported by both republican parties: the SDLP leader has said that Brokenshire cannot serve as an “independent arbiter” of the talks, while Sinn Fein’s Gerry Adams has described the incipient Tory–DUP deal as one “that undercuts . . . the process here of the Good Friday and other agreements,” and he has turned to the Irish government for some sort of mediation.

The second concern is that the Tories’ confidence-and-supply agreement with the DUP may make the formation of a government simply impossible, thus hastening direct rule. Brokenshire has stated that the new June 29 deadline for an agreement is absolute; there will be no further extensions. If the parties do not agree by then, direct rule is a serious possibility, if not a likelihood.

The consequences could be dire. The two countries sharing the island of Ireland face in the coming two years one of their most dreadful quandaries in the last century, as the United Kingdom’s ongoing process of leaving the European Union threatens to make the border between the north and the Republic a hard one. The virtually invisible Irish border, a hallmark of the peace engendered by the Good Friday Agreement, may soon become a thing of the past.

In a certain conception, cooperating with the DUP to prop up the government may, just perhaps, prove a saving grace. Like all Northern Irish parties, the DUP opposes instituting a hard border, believing it would impede the free flow of people and goods across the island. If the price of the DUP’s support is a sustained Tory effort to ensure the continued ease of movement to and from Ireland, the cooperation may at least point in the right direction. But though the DUP does support an open border, it’s not altogether clear that it is their most immediate political priority; Foster may be more interested in wringing money out of Her Majesty’s Treasury (partly to cover for the failed heating scheme).

In any case, the DUP’s quasi-introduction into government only makes the process of bargaining for the region’s post-Brexit future harder. This is an endeavor that will require sustained cooperation — not just among the parties of Northern Ireland, but also between those parties and the governments of Ireland and the United Kingdom, and between those two governments themselves. The Good Friday Agreement provides an adequate basis on which to conduct these complex negotiations; it has, after all, brought a remarkable end to three decades of bloody civil war. Theresa May would do well to tread carefully: Political expedience is no justification for risking the end of a successful, yet delicate, settlement.